Regardless of your hardware, upgrading to Windows 7 will unlikely solve any issues you may be experiencing. Windows 7 retains the Windows Aero user interface and visual style first introduced with its predecessor, Windows Vista, and although many areas have seen enhancements, the interface is still processor and memory intensive. As a result, a better option would be to upgrade to Windows 8. Windows 8 lacks Aeroglass which was a large resource hog on slower machines. As a result, it has a smaller memory footprint. There are also numerous other changes which can affect performance, including WDDM 1.2 which further offloads processing to the GPU, and the inclusion of Windows Defender.
Also, it's doubtful that anyone here will supply you with a legitimate copy of either operating system. With a little research, you may be able to find bootleg versions elsewhere.